Toothed piece for a geared motor, series of geared motors and connection

ABSTRACT

In a toothed piece for a geared motor, series of geared motors and connection, the toothed piece, for a connection with a motor shaft of the electric motor, having at least a first toothing in a first axial region, and having at least a second toothing in a second axial region, the second toothing meshing with a running toothing of a further toothed piece of the gear unit.

FIELD OF THE APPLICATION

[0001] The present invention relates to a toothed piece for a geared motor, a series of geared motors and a connection.

[0002] The U.S. Pat. No. 3,242,998 A describes a toothed piece, driven by a toothed motor shaft, for a connection to an output shaft, which has a first toothing in a first region and a second toothing in a second region. In this case, an internal toothing must be produced in a complicated and expensive manner.

[0003] A shank pinion is also known as a toothed piece from the European Patent 0 989 316 A1. However, during mounting, centering may only be provided in a costly manner.

[0004] In the German Patent 26 07 363 C3, the toothed piece has two helical toothings; however, centering during mounting is again costly.

[0005] The German Patent 296 03 748 U1 describes a pin for an adapter, the pin being usable for centering upon insertion.

[0006] Geared motors are known whose motor shaft drives an externally-toothed pinion, whose toothing meshes with an externally-toothed gear wheel having a running toothing.

[0007] To reduce noise, involute toothings having a non-vanishing helix angle are used for these toothings. The disadvantage in this case is that, during the transmission of torque, axial forces develop which must be absorbed by further components such as bearings.

[0008] Therefore, the object of the present invention is to further develop a pinion for a geared motor in such a way that less expensive parts may be used in the gear unit or, in a more cost-effective manner, parts may even be omitted in the gear unit.

[0009] According to the present invention, the objective is achieved in the toothed piece for a geared motor according to the features indicated in claim 1, in the toothed piece for a geared motor according to the features indicated in claim 16, and in the connection according to the features indicated in claim 17.

[0010] Essential features of the present invention with respect to the toothed piece are that, for a connection to a motor shaft of the electric motor, the toothed piece has at least a first toothing in a first axial region, and at least a second toothing in a second axial region, the second toothing meshing with a running toothing of a further toothed piece of the gear unit. In this context, it is advantageous that the second toothing may be implemented with a different pitch circle diameter than the first toothing. Therefore, on the motor side, different toothed pieces are useable within one size for different variants; the toothed pieces are able to be implemented with always the same first toothing on the motor side, and with different second toothings on the gear unit side. In this way, a motor shaft of the same kind may be used within the size for each variant, it being possible to realize different transmission ratios at the first input stage of the gear unit. Another important advantage is that a high torque is able to be transmitted from the motor shaft to the toothed piece with the aid of the first toothing.

[0011] In one advantageous embodiment, the motor shaft has a driver toothing which meshes with the first toothing of the toothed piece. The advantage here is that not only is a high torque transmittable, but the toothings may also be produced inexpensively using industrially common toothing machines.

[0012] In one advantageous development, the first and second toothings are each helical toothed and have the same algebraic sign for the helix angle and/or have the same helix angle. This offers the advantage that the components of axial force, generated by the helical toothings, onto the toothed piece itself may be influenced in the design by the selection of the helix angles and the toothing data in such a way that a reduced, resulting component of axial force onto the toothed piece itself is attainable. Essential improvements in the design of the gear unit may be achieved by this reduction in the resulting axial force onto the toothed piece itself. Other parts may be implemented more cost-effectively or even dispensed with, such as suitable retaining rings or the like.

[0013] In one advantageous refinement, the first and second toothings are involute toothings. The advantage in this case is that such industrially common toothings may be produced inexpensively, easily and quickly on suitable production machinery.

[0014] In one advantageous development, the first and/or second toothing is/are external toothings. The advantage here is that the toothed piece has a compact form and therefore may be produced inexpensively. In particular, external toothings may be manufactured simply, quickly and inexpensively using large milling cutters, and after the hardening, using large grinding wheels.

[0015] In one advantageous embodiment, the pitch circle diameter of the first toothing is larger than the pitch circle diameter of the second toothing. Of advantage in this case is that a smaller gear wheel may also be used in the first gear stage, including second toothing of the shank pinion and gear wheel, which means it is also possible to realize small transmission ratios.

[0016] In one advantageous form, the toothed piece has, at its motor-side end, a pin which is inserted in such a way into a corresponding cut-out in the motor shaft that, upon insertion into the cut-out, it may be used for centering the toothed piece. This offers the advantage of easy and quick production. In particular, the centering also permits a highly precise, and at the same time, quickly executable assembly.

[0017] In one advantageous refinement, the pin is cylindrical. The advantage here is that the pin may be produced inexpensively.

[0018] In one advantageous refinement, the pin is conical. This offers the advantage that assembly may be accomplished particularly quickly, and even if the toothed piece deviates from the ideal position prior to or during assembly, a centering takes place, as it were, automatically correctly upon insertion into the motor shaft.

[0019] In one advantageous embodiment, the pin has a knurling. The advantage in this case is that the knurling has a greater hardness than the material of the motor shaft, and therefore is able to be pressed into the motor shaft, accompanied by material deformation. Therefore, in the case of small torques, the connection of the toothed piece to the motor shaft is implemented via this press connection. Only after a critical torque is exceeded is the driver toothing of the motor shaft usable with the first toothing of the toothed piece for the torque transmission.

[0020] In one advantageous development, the toothed piece has a cutout which, upon introduction into the motor shaft, is useable for centering the toothed piece. The advantage in this connection is that the toothed piece has only a short length, and therefore needs less storage space and assembly space; in particular, it is rotatable on a smaller space volume during the assembly. It also has less volume of material. This is advantageous, since, particularly because of the higher torque to be transmitted and the greater hardness for the machine grinding of the toothings, the material of the toothed piece is more expensive than the material for the motor shaft, for which structural steel may also be used.

[0021] In one advantageous refinement, the first and second toothings are included by a single toothing. This offers the advantage that production is particularly simple, and a high transmission ratio may be realized.

[0022] In one advantageous development, the driver toothing of the motor shaft is an inner toothing. This is advantageous because it may be produced inexpensively using industrially common production methods, particularly by striking, broaching, original forming and/or milling.

[0023] Essential features of the present invention with respect to the series of geared motors are that the series includes at least one size, and each size includes one or more variants of geared motors; within one size, substantially identical motor shafts, which in each case are connectible and/or connected to a toothed piece, are usable for different variants; within one size, at least one variant includes a toothed piece whose first and second toothings are different; and at least one further variant includes a toothed piece whose first and second toothings are identical. In this context, it is advantageous that, by the use of different toothed pieces, it is possible to realize a wide range of different transmission ratios. In particular, not only the toothing data may be varied, accompanied by an essentially constant pitch circle diameter, but also the pitch circle diameters may be varied within one size for the variants. This enlarges the range of transmission ratios considerably.

[0024] In addition, it is possible to use an involute toothing as a first toothing, and as a second toothing, to use a pinion for a helical-bevel gear stage, or a pinion for another type of gear stage such as, for example, a planetary gear stage, a gear stage having a spiroidally toothed wheel or other bevel gear stages. Therefore, even a motor shaft which is always substantially identical may be used for various types of the input gear stage.

[0025] Essential features of the present invention with respect to the connection from a first rotating part via a toothed piece to a part having a running toothing are that the toothed piece has a second toothing which meshes with the running toothing; and that the toothed piece has a first toothing which meshes with a driver toothing of the first rotating part; and that the helix angles of the first and the second toothing are selected in such a way that the direction of the axial force, generated by the driver toothing and first toothing, onto the toothed piece itself, and the direction of the axial force, generated by the running toothing and second toothing, onto the toothed piece itself are opposite, in order to decrease the resulting axial force onto the toothed piece itself. This offers the advantage that the components of axial force, generated by the helical toothings, onto the toothed piece itself may be influenced in the design by the selection of the helix angles and the toothing data in such a way that a reduced, resulting component of axial force onto the toothed piece itself is attainable. Essential improvements in the design of the total device may be achieved by this reduction in the resulting axial force onto the toothed piece itself. Other parts may be implemented more cost-effectively or even dispensed with, such as suitable retaining rings or the like.

[0026] Further advantageous developments are yielded from the dependent claims.

[0027] Reference Numeral List

[0028]1,21,63 first toothing

[0029]2,22,64 second toothing

[0030]3, 23, 42, 51, 61, 71 shank pinion

[0031]31 motor

[0032]32, 41 motor shaft

[0033]33 cut-out

[0034]34 driver toothing

[0035]43 cylindrical pin

[0036]44 gear wheel

[0037]52 conical pin

[0038]62 cut-out

[0039]72 pin with knurling

[0040]81 shank pinion

[0041]82 toothing

[0042] The invention shall now be explained in detail with reference to a drawing.

[0043]FIG. 1 shows a shank pinion 1 which has a first toothing 1 and a second toothing 2, first toothing 1 having a smaller pitch circle diameter than second toothing 2. First toothing 1 and second toothing 2 each have a negative helix angle of the same amount. In other exemplary embodiments of the present invention, different amounts may also be used.

[0044]FIG. 2 shows a shank pinion 23 which has a first toothing 21 and a second toothing 22, first toothing 21 again having a smaller pitch circle diameter than second toothing 22. First toothing 21 and second toothing 22 each have a positive helix angle of the same amount.

[0045] The helix angle is denoted symbolically in FIGS. 1 and 2 by three parallel marks. In the figures, M designates the motor-side axial end of the shank pinion, and G designates the axial end of the shank pinion on the gear unit side.

[0046] In FIG. 3, a motor 31 is partially indicated, whose motor shaft 32 has a bore hole having a driver toothing 34, implemented as an inner toothing, with which first toothing 1, 21 of shank pinion 3, 23 meshes.

[0047] In addition, the motor shaft has a cut-out 33 for centering a shank pinion provided with a corresponding pin. In other exemplary embodiments of the present invention, motor shaft 32 may be implemented without a cut-out, shank pinions 3, 23 according to FIG. 1 or 2 then being used.

[0048]FIG. 4 shows a shank pinion 42 which has a cylindrical pin 43 for centering upon insertion into motor shaft 41. With second toothing 2 as running toothing, shank pinion 42 meshes with gear wheel 44 of the gear unit.

[0049] Driver toothing 45, designed as a helical toothing and meshing with first toothing 46 likewise designed as a helical toothing, generates a component of axial force onto the toothed piece. The running toothing of gear wheel 44, together with the second toothing of shank pinion 42, generates an oppositely directed component of axial force onto the toothed piece itself. Therefore, the resulting component of axial force onto the toothed piece itself has only a small or even vanishing value, depending upon the selection of the helix angles and the toothing data.

[0050]FIG. 5 shows a shank pinion 51 having a conical pin 52 for the centering in a correspondingly conical cut-out and/or bore hole in the motor shaft.

[0051]FIG. 6 shows a shank pinion 61 which again has a first toothing 63 and a second toothing 64. In addition, shank pinion 61 has a cut-out 62 for the centering, the motor shaft having a corresponding form or, in other exemplary embodiments of the present invention, the motor shaft being provided with corresponding parts.

[0052]FIG. 7 shows a shank pinion 71 having a pin provided with a knurling 72. Since shank pinion 71 is made of a hardened material and/or a material having a greater hardness, shank pinion 71 is able to be pressed into the softer motor shaft, made of structural steel, accompanied by material deformation.

[0053] Instead of structural steel, other materials may also be used which are less hard than the shank pinion.

[0054]FIG. 8 shows an advantageous further development of the present invention, shank pinion 81 having a helical-toothed toothing 82 which, on the motor side, meshes with the correspondingly helical-toothed driver toothing of the cut-out of the motor shaft, and on the gear unit side, meshes with the running toothing of a correspondingly helical-toothed gear wheel of the gear unit. Therefore, it is only necessary to produce a single toothing, which is particularly simple and cost-effective.

[0055] Thus, shank pinions according to FIG. 8, for which toothing data such as, in particular, root diameter, outside diameter and pitch circle diameter of the first and of the second toothing are identical, may be used in a series of gear units having several gear ratios within one size. In addition, shank pinions according to FIG. 1 are usable with the same motor shaft. Since, therefore, different shank pinions having, in each case, a different second toothing but identical first toothing may be used, it is possible to realize a wide range of transmission ratios.

[0056] In further specific embodiments of the present invention, the inventive idea may also be used for other types of toothing. For example, the first toothing of the shank pinion is a helical-toothed involute toothing, and the second toothing meshes with a bevel gear or a spiroidally toothed wheel. Thus, cylindrical or non-cylindrical second toothings are also feasible.

[0057] In other specific embodiments of the present invention, the invention may be used not only for gear units, but also for other devices which include a connection from a first rotating part, such as a shaft, via a toothed piece to a part having a running toothing. In this context, in the manner shown in the figures, the toothed piece may be designed with a first and second toothing, each having the same algebraic sign of the helix angle, such that the axial force components generated in each instance act in the opposite direction. Therefore, the advantages and effects indicated may also be achieved for other devices. 

What is claimed is:
 1. A toothed piece of a geared motor, that includes at least an electric motor and a gear unit, wherein the toothed piece for a connection to a motor shaft of the electric motor, has at least a first toothing in a first axial region, and has at least a second toothing in a second axial region, the second toothing meshing with a running toothing of a further toothed piece of the gear unit.
 2. The toothed piece as recited in at least one of the preceding claims, wherein the first axial region is disposed on the motor side, particularly at the motor-side end of the toothed piece, and the second axial region is disposed on the gear unit side, particularly at the end of the toothed piece on the gear unit side.
 3. The toothed piece as recited in at least one of the preceding claims, wherein the motor shaft has a driver toothing which meshes with the first toothing of the toothed piece.
 4. The toothed piece as recited in at least one of the preceding claims, wherein the toothed piece is a shank pinion.
 5. The toothed piece as recited in at least one of the preceding claims, wherein the first and the second toothings are each helical toothed and have the same algebraic sign for the helix angle and/or have the same helix angle.
 6. The toothed piece as recited in at least one of the preceding claims, wherein the first and second toothings are involute toothings.
 7. The toothed piece as recited in at least one of the preceding claims, wherein the first and/or second toothing is/are external toothings.
 8. The toothed piece as recited in at least one of the preceding claims, wherein the pitch circle diameter of the first toothing is larger than the pitch circle diameter of the second toothing.
 9. The toothed piece as recited in at least one of the preceding claims, wherein at its motor-side end, the toothed piece has a pin which is inserted into a corresponding cut-out of the motor shaft in such a way that, upon insertion into the cut-out, it is usable for centering the toothed piece.
 10. The toothed piece as recited in at least one of the preceding claims, wherein the pin is cylindrical.
 11. The toothed piece as recited in at least one of the preceding claims, wherein the pin is conical.
 12. The toothed piece as recited in at least one of the preceding claims, wherein the pin has a knurling.
 13. The toothed piece as recited in at least one of the preceding claims, wherein the toothed piece has a cut-out which, upon introduction into the motor shaft, is usable for centering the toothed piece.
 14. The toothed piece as recited in at least one of the preceding claims, wherein the first and second toothings are included by a single toothing.
 15. The toothed piece as recited in at least one of the preceding claims, wherein the driver toothing of the motor shaft is an inner toothing.
 16. A series of geared motors, the series including at least one size, and each size including one or more variants of geared motors, and within one size, substantially identical motor shafts are usable for different variants, the motor shafts in each instance being connectible and/or connected to a toothed piece as recited in at least one of the preceding claims, within one size, at least one variant including a toothed piece whose first and second toothings are different, and at least one further variant including a toothed piece whose first and second toothings are identical.
 17. Connection from a first rotating part via a toothed piece as recited in at least one of the preceding claims, to a piece having a running toothing, the toothed piece having a second toothing which meshes with the running toothing, and the toothed piece having a first toothing which meshes with a driver toothing of the first rotating part, and the helix angles of the first and the second toothing being selected in such a way that the direction of the axial force generated by the driver toothing and the first toothing, and the direction of the axial force generated by the running toothing and the second toothing are opposite, in order to reduce the resulting axial force. 